Process for carrying out ion exchange and adsorption processes using a countercurrent vessel

ABSTRACT

Ion exchange and adsorption processes are carried out in a countercurrent vessel in which the washing liquid is purified in a covering layer situated on a partition in the vessel, which layer preferably consists of the same ion exchange material, before it enters the ion exchange mass.

t United states Patent I 1 [111 3,875,053 Siegers Apr. 1, 1975 I5PROCESS FOR CARRYING OUT 1m. 3.340.699 3mm Duffel al 210 EXCH \'(;E ANDADSORP-HON 3.4Ull2h 9/1968 Cioffi BIO/35 ammu x1197: Emmett 210/279 xPROCESSES [SING A C(flNTERCl'RRENT VESSEL lmentor: (iunter Siegers.Schildgen. Germany {73] Assignec: Bayer Aktiengesellsehaft.

Leverkusen. Germany [ZZI Filed: Apr. 25. 1973 [I 1] Appl, 51053541127[30] Foreign Application Priority Data May 3. 73 (iermany n 2221561 [52}Cl 210/35, 210/269. 210/285. 210/291 I51] Int. Cl. BOld 15/06 [5K] Fieldof Search /35. 279. 30. 275. 269. 210/285. 29l

[56] References Cited UNITED STATES PATENTS 3.855.364 10,1958 Roberts210/35 FOREIGN PATENTS OR APPLICATIONS 2.()l7.l3l lU/l97l German lid/279Primary btuminerFrank A. Spear. Jr. Asxw'sum! Iitaminw-Ferris H. LanderAttorney. Agent. or FirmBurgess. Dink-age & Sprung [57] ABSTRACT ionexchange and adsorption processes are carried out in a countercurrentvessel in which the washing liquid is purified in a covering layersituated on a partition in the vessel. which layer preferably consistsof the some ion exchange material. before it enters the ion ex changemass.

2 Claims. 1 Drawing Figure PROCESS FOR CARRYING OUT ION EXCHANGE ANDABSORPTION PROCESSES USING A COUNTERCURRENT VESSEL This inventionrelates to a process for carrying out ion exchange and adsorptionprocesses using a countercurrent vessel through which the liquid whichis to be treated flows upwards. passing through an exchange materialwhich is situated between a lower nozzle plate and a partition which isprovided with both discharge and throughtlow duets while. in theregeneration phase, a regenerating liquid entering the upper part of thecontainer flows downwards through the exchange ma terial and in theback-wash phase the resin is flushed back upwards.

In all ion exchange systems operating by the countcrcurrent process itis important to prevent movement of the layer of ion exchange material.

In the vessel described above. no movement or shifting of the ionexchange material occurs if the space between the two nozzle plates iscompletely filled with ion exchange material and. in addition. resin inan amount of up to 507: of the quantity of active ion exchanger used isplaced on the upper nozzle plate. in a so-called back flushing chamberarranged above it.

In other countercurrent systems shifting of the ioncxchange material isprevented by exerting pressure on a covering layer placed on theexchange material while regenerating liquid is passed upwards. Dynamicor static techniques may be employed for this purpose; water or air maybe used to apply pressure to the upper layer of the exchange material orclosable nozzle plates or inflatable rubber bladders may be fitted.

According to another embodiment. the exchange material is placed betweentwo nozzle plates and is pressed against the upper nozzle plate whilethe liquid which is to be treated flows through the apparatus.

When using the countercurrcnt system described above. however. the ionexchange material is forced upwards through apertures in the partitionwhen the material is back-washed.

A common feature of all countercurrent processes is the fact that theliquid which is to be treated last contacts the exchanger layer whichwas the first to be in contact with the regenerating liquid during thepreceding regcneration process and which therefore underwent the highestdegree of regeneration.

The quality of the treated liquid depends mainly on the extent to whichthis uppermost layer is purified. For this reason. the regeneratingliquid is rinsed out and displaced by a rinse liquid for example water,which is of at least equal purity with the preceding effluent of theexchange unit. If a rinse liquid of lower purity is used then theuppermost layer, the so-called polishing layer. is contaminated with acertain preliminary charge which has a damaging effect on the degree ofpurity of the liquid to be treated. This disadvantage is obviated bydrawing the necessary rinse liquid from the reservior of treated liquidor from a purification plant working in parallel with the unit, whichreservior must of course be sufficiently large.

It is an object of this invention to provide a process which does notrequire the use of treated liquid for rinsing the exchange material andin which it is no longer necessary to supply a rinse liquid of equalpurity to the treated liquid.

The invention therefore provides a method for carrying out an ionexchange or adsorption process using a counter current vessel whichvessel comprises a container. a lower plate provided with one or morenozzles and an upper plate which is provided with one or morethroughflow apertures and one or more discharge tubes. in whichcontainer the space between said upper and said lower plates is tilledwith ion exchange mate rial or adsorbent and the upper plate is coveredwith a layer of ion exchange material or adsorbent. which may be thesame as or different from the material contained between the two plates.which method comprises an activation or regeneration phase in which theactivating or regenerating liquid enters the container at the top andflows downwards through the covering layer and the material between theplates. at rinsing phase in which rinse liquid enters the container atthe top and flows downwards through the container. thereby displacingthe activating or regenerating liquid. and a treatment phase in whichthe liquid to be treated enters the container at the bottom flowsupwards through the material located between the plates. leaving thecontainer via said discharge tubes.

Another advantage of the process is that the fine particles of ionexchange material formed during operation of the vessel. which duringthe charging phase may cause considerable difficulties. such asincreased pressure loss and flow obstructions. if subjected to liquidsflowing at high velocities. need only be removed if their volume exceedsthe quantity of covering layer situated above the partition. Nohydrodynamic difficulties are to be expected in the regeneration phasein which the flow is directed downwards at very much lower velocities.It is sufficient if. in the course of the back flushing operations whichare periodically required. the fine particles are transported from thepart of the filter bed which is active during the charging phase intothe space situated above the perforated partition. In that situation,the fine particles replace the intact or suitably sized ion exchangeparticles which inevitably fall into the region between the two nozzleplates where they actively take part in the ion exchange process.

The quantity of ion exchanger which constitutes the covering layer abovethe perforated partition must be such that when the rinse water for themass resin which is active during the charging phase passes through it.it will never be completely charged. The quantity of covering layer onthe partition is preferably 5 to 507: by volume of the active ionexchanger mass. A countercurrent system suitable for the process isshown purely diagrammatically in the accompanying drawing and its modeof operation is described below.

The countercurrent vessel consists of a container 1) having a lowernozzle plate (2). About halfway up the container (I) is a partition (3)with individual nozzles (4) from which discharge tubes (5) are connectedto a discharge pipe (6) which leads to the outside. In addition, thepartition (3) has flowthrough apertures (7). The space between thenozzle plate (2) and partition (3) is completely filled with ionexchange material (8). A covering layer (9) is situated on the partition(3). In addition. the container 1) has an inlet and outlet aperture (10)at the bottom and (II) at the top.

During the back washing process. the back washing liquid enterscontainer I) through the pipe (10) below the nozzle plate (2) and isdistributed over the crosssection of container (1) through the nozzleplate (2) before entering the ion exchange material (8). The liquidraises the exchange material (8) which is thereby partly forced throughthe apertures (7) of partition (3) into the space (12) above it. Theback-washing liquid leaves the container l through the opening I l Thenozzles (4) of the partition (3) and the main conduit (6) are closedduring this phase. After completion of the back-washing process. the ionexchange material (8) returns through the apertures (7) to settle at itsprevious level. During this process, the fine particles from the regionof active ion exchange material 8) are replaced by coarser material fromthe inactive covering layer (9) situated above the partition (3).

During the regeneration process, the regenerating liquid enters theupper part of the container through the opening (H) and flows downwardsfirst through covering layer (9) and then through the ion exchangematerial (8) and finally leaves the container (I) through the opening(10) at the bottom of the container.

After the regeneration process, the regenerating liquid must be rinsedout of the ion exchange material (8) and displaced. The rinse liquidrequired for this operation also enters the top of the container lthrough the inlet opening (11) to reach the covering layer (9). Since,as already mentioned above, it is permissible to use a quality of rinseliquid similar to that of the liquid which is to be purified, the ionexchange material (8) on the surface of the covering layer (9) becomespartly charged to an extent which depends on the volume of rinse liquidand the concentration of ions in it. For washing the active ionexchanger. it is sufficient to use 2 to 4 times the volume of the activeexchanger be tween the lower and upper plates.

Consequently, only a relatively small part of the covering layer (9),directly on its surface, becomes charged. Since that part of theexchange material (8) which is adjacent to the covering layer (9) onlycomes into contact with already purified rinse water during the rinsingphase, there is no possibility of a preliminary charge influencing thesubsequent quality of the filtratc.

The solution which is to be purified is introduced into the container 1through the inlet opening l) during the subsequent charging phase, flowsthrough the lower nozzle plate (2) and ion exchange material (8) andenters the nozzle (4) ofthe partition (3) to leave the container (I)through the duct and main conduit (6). During this process. the opening(ll) remains closed.

EXAMPLE I To remove the cations from a solution, a total 119 li ters ofan ion exchanger which had been prepared by sulfonating polystyrenecross-linked with divinyl benzene was introduced into a cylindricalcontainer. liters ofthe aforesaid I I9 liters of cation exchanger weresituated as covering layer above the perforated nozzle plate. Theremaining 99 liters took part in the ion exchange process. Thecountercurrent filter had a diameter of 300 mm and the cylindrical parthad a total height of 2400 mm. As indicated in the accompanying drawing,the container contained a nozzle plate (2) at the lower end and, 1400 mmabove it, a second nozzle plate (3). which immediately around eachnozzle was provided with flowthrough apertures (4) 15 mm in diameter forthe throughflow of the ion exchanger. Each of the nozzle plates hadseven filter nozzles nozzles per in) For the regeneration process, theregenerating acid entered the container I through the pipe l l passedfirst through the covering layer (9) and then through the apertures onthe perforated nozzle plate (3) through which ion exchange materialpasses in the back-washing phase, then through the active resin material(8) which such was regenerated and then through the lower nozzle plate(2), finally leaving the filter I) through pipe (10). The untreatedwater used for displacing and rinsing away the regenerating acid tookthe same path.

147 Val ofhydrochloric acid L48 Val/l of active exchanger) at aconcentration of LI Val/l of solution were filtered through all the ionexchange material in the container within 22 minutes in the mannerindicated above. 232 liters of untreated water having a cation contentof 9.3 mVal per liters (38.7% Na", 4671 Ca and l5.3"/r Mg) were requiredfor displacing and rinsing the acid.

During the subsequent exhaustion with water of the above composition,I28 rn could be completely freed from cations, the water entering thecontainer (1) through the opening (10) at the rate of 2.5 m /hour andflowing through the ion exchange material (8) and nozzles (4) of thepartition (3) to leave the filter in a purified state through theconduit (5) and main pipe (6).

The effluent from a strongly basic ion exchanger connected to thedownflow end of the above mentioned filter was found to have an averageconductivity of 2.98 microsicmens/cm. The water flow through the cationexchanger was stopped when the conductivity was 15 microsicmens/cm.

The same output, namely 12.79 m" of pure water with an averageconductivity of 3.1 l microsicmens/em, was measured in an experimentwhich differed from the preceding experiment in the rinsing process butwas identical in every other respect. 225 liters of demincralized waterentering through the main pipe (6), conduits (5) and nozzles (4) wereused for rinsing. In yet another cxperiment which was carried out afterregeneration and rinsing with untreated water and in which bothregenerating solution and rinse water were introduced through the mainpipe (6) and discharged through the opening (7) at the bottom of thecontainer, subsequent treatment with untreated water of the abovecomposition yielded only l2.4 m of pure water. The effluent of astrongly basic anion exchanger was found to have an average conductivityof 35.4 microsicmens per cm. The water flow was in this case stopped at50 microsicmens because values below 15 microsicmens/cm could not beachieved.

EXAMPLE 2 A total of 950 liters of an anion exchange material preparedby introducing dimethyl-ethanolamine groups into polystyrenecross-linked with divinyl benzene were introduced into a cylindrical ionexchanger vessel (l) which had a diameter of 820 mm and a totalcylindrical height of 2500 mm and which contained a nozzle plate (2)with filter nozzles (4) at the lower end and, 1500 mm above it, aperforated partition (3) also provided with filter nozzles (4). Thenozzle plate and partition were provided with 52 filter nozzles each.Four flowthrough apertures (7) with a diameter of 18 mm for passage ofthe ion exchanger material (8) were uniformly positioned about eachnozzle (4) of partition (3). Each nozzle (4) of partition (3) wasconnected to a main pipe (6) through conduits (5).

The 792 liters of ion exchange material (8) situated between the lowernozzle plate (2) and partition (3) were used for the actual operatingprocess. The remaining I58 litres formed a 30 cm high layer (9) abovethe perforated partition (3). The remaining space 12) above tilter layer(9). which had a cylindrical height of about 800 mm. was used for thehack washing process.

Sodium hydroxide solution used for the process of regeneration enteredthrough the opening ll to flow through the layer (9) and ion exchangematerial (8) and was discharged through the opening U0). The water usedfor rinsing and displacement of the regenerating liquid. which wassupplied from an adjacent cation exchanger vessel in which untreatedwater was passed through resin charged with H ions. subsequently flowedalong the same path.

After regeneration with 750 Val of NaOH at a concentration 0.5 Val/l ofsolution and rinsing until the conductivity was reduced to 30 S/cm.which required 2620 l of the effluent from an adjacent cation exchanger.the filter was charged with decationized water of the followingcomposition:

Cl co 4.3 mval/l'. (1.23 nival/l.

lhl mval/l; (Ll l7 mval/l,

put of l02.0 m" and a residual SiO content of 0.023 mg/l.

A further experiment which was carried out after regeneration andrinsing with cation exchanger effluent and in which both liquids wereintroduced backwards through the main pipe (6) and discharged throughthe opening (10) yielded distinctly inferior results, namely an outputof only 97.1 m and an average residual SiO. content of 0.0096 mg/l.

We claim:

I. A method for carrying out ion exchange or adsorption employing acontainer provided with inlet-andoutlet tubes adjacent the top andbottom. an intermediate inlct-ancl-outlet tubc and a lower plate forretaining solid ion exchange or adsorption material while permittingpassage of liquid. comprising filling said container with ion exchangeor adsorption material to a level above the level of communicationbetween the container and the intermediate tube. so as to form an activelayer of material extending from the container bottom to saidintermediate tube communication level surmounted by a covering layer ofmaterial above said intermediate tube communication level, passingactivating or regenerating liquid from said top tube downwardly throughall said material and out said bottom tube. passing sufficient untreatedliquid to serve as a rinse liquid from said top tube downwardly todisplace substantialaly all of said activating or regenerating liquid.passing liquid to be treated upwardly from said bottom tube and out saidintermediate tube without backing up into said covering layer until thecapacity of the ion exchange or adsorption material is significantlydiminished. and then repeating the sequence of steps.

2. A method as claimed in claim 1 in which the volume of the coveringlayer is between 5'?! and 50'? of the volume of the active layer ofmaterial.

* t t k

1. A METHOD FOR CARRYING OUT ION EXCHANGE OR ADSORPTION EMPLOYING ACONTAINER PROVIDED WITH INLET-AND-OUTLET ADJACENT THE TOP AND BOTTOM, ANINTERMEDIATE INLET-AND-OUTLET TUBE, AND A LOWER PLATE FOR RETAININGSOLID ION EXCHANGE OR ADSORPTION MATERIAL WHILE PERMITTING PASSAGE OFLIQUID, COMPRISING FILLING SAID CONTAINER WITH ION EXCHANGE ORADSORPTION MATERIAL TO A LEVEL ABOVE THE LEVEL OF COMMUNICATION BETWEENTHE CONTAINER AND THE INTERDEDIATE TUBE, SO AS TO FORM AN ACTIVE LAYEROF MATERIAL EXTENDING FROM THE CONTAINER BOTTOM TO SAID INTERMEDIATETUBE COMMUNICATION LEVEL SURMOUNTED TUBE A COVERING LAYER OF MATERIALABOVE SAID INTERMEDIATE TUBE COMMUNICATION LEVEL, PASSING ACTIVATING ORREGENERATING LIQUID
 2. A method as claimed in claim 1 in which thevolume of the covering layer is between 5% and 50% of the volume of theactive layer of material.